"She was my baby, and we stood together throughout Brittany's life. Now I must stand up for her again," writes Sharon Murphy exclusively for The Hollywood Reporter days after the late actress' estranged biological father claimed a new lab test showed evidence of possible foul play.

I have chosen to stay out of the limelight since the tragic and sudden death of my wonderful, talented, loving daughter four years ago this Dec. 20.

From the day of her birth, Brittany was my precious, more dear to me than anything or anyone in the universe. I have been devastated by her loss and that of my son-in-law [SimonMonjack] and have remained in seclusion in my mourning.

I have no choice now but to come forward in the face of inexcusable efforts to smear my daughter's memory by a man who may be her biological father but was never a real father to her in her lifetime. Angelo Bertolotti has relocated to California in his old age to claim he is here for Brittany, as he never was in life. He has made outrageous statements over the past few years, culminating in this latest madness: that my darling daughter was murdered.

His claims are based on the most flimsy of evidence and are more of an insult than an insight into what really happened, as I will explain to you shortly.

First, I want you to know a little of the real story. I raised Brittany alone. We didn't have much at first, but we always had each other. My daughter and I were our only family, and we were inseparable and always there for each other in good times and bad. She never left my side as I battled cancer twice, and I was there for her through the trials and tribulations of her beautiful life and career.

Angelo was not there at all after age 1. He certainly wasn't around during the 12 years he spent in prison on three criminal felony convictions. Throughout her childhood, I was Brittany's only parent and sole support. No bond could have been stronger.

Angelo did come out of the woodwork when Brittany was a teenager and found success in a number of TV shows just before she was in Clueless. But she quickly saw him for who he is -- and didn't want anything to do with him. He now claims to have had a few meetings with Brittany over the years where he took the occasional photograph, but those must have been brief moments because I was there with her most of the time at home and when she was working -- and he was never, ever around. He has admitted he did not see her at all during the final three years of her too-short life.

It sends pain through my heart when I read [in recent reports about Bertolotti's lab testing results] that "the family said" -- meaning Angelo -- because he was never her family in reality. She and I and our extended family and close friends were her family, and as she grew in years and professionalism, she was beloved by many, many people, including fellow performers and the great artists in Hollywood.

In light of the recent publicity about a lab test Angelo had done, I have asked some knowledgeable people, and they tell me that an analysis from a sample of hair is not considered dependable unless it is backed up by tests of tissue and blood and other analysis -- which he did not do (the coroner did, but they show no similar results). I am also told one lab may give different results than another lab in terms of heavy metals, and the proper method requires multiple tests before any results are released.

The lab Angelo used, if you can call it that, is an Internet site that farmed out the actual testing and then wrote horribly untrue things under the guise of "analysis." It mentioned rat poison as a possible cause and claimed to be able to say that a third party murdered my beloved daughter.

To even mention that the heavy metals that were listed in his test are in rat poison, leading to articles suggesting Brittany ingested that or anything like it, is absurd. If she had, don't you think it would have shown up in the coroner's test of her blood and tissue? A reputable expert will tell you that what this lab did is an ethical violation of the highest order; to even pretend to be able to draw such conclusions on unreliable evidence is the real crime.

This report conveniently ignores what any good scientist will tell you: A hair sample can be affected by many outside factors, including hair dye, hair spray, prescription medications, foods, smoking the occasional cigarette and environmental factors. One cause we now know may have been toxic mold that was eventually discovered in that house -- which may have been what really killed her.

We will never know for sure. However, we do know the Los Angeles County Coroner did extensive tests and found that she died of natural causes. And now she is a real living angel in heaven.

Angelo has also formed the Brittany Murphy Foundation, as if he is fit to carry on her memory. Like everything else Angelo and his collaborator Julia Davis have done, this is calculated to make them money and bring them the fame they desperately crave. They say they want to do a documentary and write a book, and this whole stunt is merely publicity to fuel their aspirations.

I can only imagine the horror that would be in that book and documentary, based on what has been said in Davis' earlier work, The Terror Within. Davis and Angelo have told bald-faced lies in order to promote their products by falsely associating my daughter and son-in-law in their story.

Let me be clear: I am quite confident Brittany never cooperated with Julia Davis, never signed any statement in support of her, never met with her and barely knew she existed. Davis did try to contact Brittany through her agent, but all she got back was a letter from CAA -- then Brittany's talent agents -- which we have, telling Davis that their client knew nothing about her claims and would not meet with her.

Davis' grievances with the government agency she worked for may be real -- and if so, I feel bad for her -- but she has no right to drag my daughter's memory into it to serve her agenda.

I am sorry to be so forthright in saying this, but the time has come to bring out into the open the lies Angelo and Davis have told now that Brittany can't defend herself. They did it simply to promote their interests, their book, Davis' documentary and career. The time has come for their false statements to be exposed and rebuked.

Angelo has shown he only wants to trade on Brittany's life, career and good reputation -- even at the cost of putting a cloud over her memory. His actions have hurt the people she actually lived with, loved and considered her dearest friends and family. I have heard from many of Brittany's closest friends about the awful things said on the Internet or in the media about them when their only crime was to truly love Brittany. This has been done by people willing to perpetuate awful lies for their own personal aggrandizement and enrichment.

Angelo and Davis will do what they do, but I can no longer remain silent. I must speak the truth. I want my Brittany to be remembered as the darling person she was, for the giant talent she showed the world (and left behind in her movie and TV appearances) and for the friendships and loving relationships that really were part of her life.

She was my baby, and we stood together throughout Brittany's life. Now I must stand up for her again. It is time for those who really knew and loved her to put those who want to exploit her on notice: Your lies will no longer be tolerated, and as long as I live will continue to be exposed.